Description of problem:
Some recent selinux update, I assume, is blocking the execution of "dot -c" from the post scripts in the graphviz-plugin-* rpms.
This prevents the creation of /usr/lib64/graphviz/config6 which is used at user runtime to identify all available plugins without loading them every time.

Without this config6 file, dot fails to find its plugins:
   $ echo "digraph {hello->world}" | dot -Tpng >hello.png
   Format: "png" not recognized. Use one of:


Version-Release number of selected component (if applicable):
graphviz-2.34.0-4.fc20.x86_64.rpm

How reproducible:
100%

Steps to Reproduce:
1.setenforce 1
2.yum install graphviz
3.

Actual results:
  Installing : graphviz-2.34.0-4.fc20.x86_64                                1/1 
warning: %post(graphviz-2.34.0-4.fc20.x86_64) scriptlet failed, exit status 127
Non-fatal POSTIN scriptlet failure in rpm package graphviz-2.34.0-4.fc20.x86_64

  
Expected results:
creation of /usr/lib64/grapviz/config6 during install

Additional info:
A workaround for now is to "setenforce 0" during install.

The simplest fix, for me (graphviz upstream), would be if selinux allowed a freshly installed /usr/bin/dot to create /usr/lib*/graphviz/config*